Variable displacement fluid device

ABSTRACT

A rotary fluid pressure energy translating device of the variable displacement type having inlet and outlet ports connected by means of a pair of working chambers each of which has a single vane primary rotor, rotatably mounted on an input shaft, the axis of which coincides with the axis of the working chambers. The single vane on each primary rotor engages the circumferential walls of its associated working chamber in a fluid sealing engagement. A secondary rotor is associated with each of the working chambers and extends therein to form a fluid sealing engagement with the inner and outer circumferential walls of the working chamber and the outer periphery of the rotor is rotatably mounted about a second shaft the axis of which is parallel to but displaced from the primary rotor input shaft. Each of the secondary rotors is provided with a recess which comes into position at the appropriate time to permit the vane to pass thereby, while maintaining the required fluid seal during the balance of the cycle of the device. Each of the working chambers has one of its circumferential walls axially shiftable relative to the opposite circumferential wall of its associated working chamber so as to vary the axial length of the working chamber and thereby reduce the effective displacement of the device. The single vanes mounted on each of the rotors are so arranged that they alternately engage the walls of their associated working chambers so as to provide a continuous displacement of fluid between the inlet and outlet ports of the device.

United States Patent Doyle V. Rowland U909 Gotlschllk Road. Plymouth. Mich.

[72] Inventor 48170 [2!] Appl. Nov 852.268 [22] Filed Aug. 22. I969 [45] Patented July 13,1971

I541 VARIABLE DISPLACEMENT FLUID DEVICE l0Clalmg4Dnwlngl-lgs.

I52] U.$.Cl .i 4l8/2l, -tl8/9,4l8l200 [5|] Int.CL.......................H..............................F0lc2lll6, F0lcl/08.F0lclll00 [50] FleldolSearch .7 l03Il20A Primary Examiner-Carlton R. Croyle Assistant Examiner-Wilbur .I. Goodlin I I I Attorney-Hau ke. Gifford and Patalidis ABSTRACT: A rotary fluid pressure energy translating device olthe variable displacement type having inlet and outlet ports connected by means of a pair ol working chambers each of which has a single vane primary rotor. rotatably mounted on an input shaft. the axis of which coincides with the axis of the working chambers. The single vane on each primary rotor en gages the circumferential walls of its associated working chamber in a fluid sealing engagement. A secondary rotor is associated with each of the working chambers and extends therein to form a fluid sealing engagement with the inner and outer circumferential walls of the working chamber and the outer periphery of the rotor is rotatably mounted about a second shaft the axis ol'which is parallel to but displaced from the primary rotor input shall. Each of the secondary rotors is provided with a recess which comes into position at the appropriate time to permit the vane to pass thereby. while maintaining the required fluid seal during the balance of the cycle of the device. Each of the working chambers has one of its circumferential walls axially shiflable relative to the opposite circumferential wall of its associated working chamber so as to vary the axial length of the working chamber and thereby reduce the effective displacement of the device. The single vanes mounted on each of the rotors are so arranged that they alternately engage the walls of their associated working chambers so as to provide a continuous displacement of fluid between the inlet and outlet ports of the device.

PATENTEB M1 3 ml SHEET 2 BF 2 rncys VARIABLE DISPLACEMENT FLUID DEVICE BACKGROUND OF THE INVENTION l. Field Of The Invention This invention relates to power transmissions and is applicable to those of the type comprising two or more fluid pressure let ports thereof provides a sealing engagement with the inner and outer circumferential walls of the working chamber. The abutment is rotatable about an axis parallel to track and the outer periphery of the vane carrying rotor forms the pumping chamber of the device. The displacement of such devices may be varied by providing one of the sidewalls thereof with means for shifting the same axially inwardly into the pumping chamber so as to decrease the volume thereof. Generally variations in the displacement of such devices is accomplished while the device is operating so that the output of the unit may be varied from full flow to zero flow while maintaining a constant input to the input shaft of the device, thus the unit is adaptable for a variety of applications in which a variable output is required while only a constant input is available.

During certain parts of the cycle of operation of pumps or chambers, whose displacement capacity it is desired to change, are closed. Moreover, ifit is desired to change the dismotor when not in operation and the parts happen to be in the position in which one of the chambers, whose displacement has to be changed, is closed, the change can only be effected slowly and with the exercise of considerable force since fluid has to be forced or drawn through working clearances.

Thus, with exi ting devices, not only is it impossible to provide for sensitive control of the displacement capacity owing to the different resistance offered through changes in the displacement at different points in the rotation of the rotor, but rapid changes in displacement both during operation and for certain positions of the rotor during idle periods may be impossible.

It has been proposed in prior art devices of this kind to provide the pump or motor with a fluid-type pressure casing in which a pressure chamber having a valve between the pres sures respectively on the highand lowprcssurc side of the pump or motor is automatically maintained by an automatic valve sensitive to the relationship between such pressures. An arrangement is provided to automatically emit fluid under pressure from the high-prcssure side of the pump to the casing fluid through the low-pressure side of the pump or motor and the casing in such a manner as maintain a desired predetermined relationship between the pressures on the highand low-pressure sides of the pump or motor and the pressure in the casing.

Such automatic valve systems have been effective in eliminating the disadvantages as discussed hereinbefore. However, such automatic valving systems have inherent disadwhich add substantially to the cost of such units. Further, since valving devices of the type required for such automatic valve systems are generally quite sensitive and require close fitting parts, they are apt to deteriorate rapidly and thus shor ten the useful life ofthe device or require maintenance thereof more often.

Devices of the type referred to hereinbefore are generally used in applications such as a garden tractor transmission in which one of the primary objects is to provide a unit which is of such devices is substantially increased.

It would therefore be desirable to provide a variable displacement unit of the type described hereinbefore which does not have any of the disadvantages of the prior art and which does not require an elaborate and complicated automatic valving arrangement to permit easy change in the displacement ofsuch units.

SUMMARY OF THE INVENTION ing, with lowand high-pressure operating passages, one of which is an inlet passage and the other is an outlet passage. The device is provided with a pair of working chambers of a generally cylindrical shape, each having a primary rotor rotatably mounted upon a common input shaft, the axis of engage, in a fluid sealing relationship, with a vane track formed within each of the working chambers so as to displace fluid from one portion thereof to another portion when the rotor rotates through a cycle of the device. Each of the working chambers is provided with an inlet and an outlet passageway, the inlet passageway of one working chamber being connected to the inlet port of the device, whereas its to the outlet port of the device thereby forming a continuous flow path from the inlet port to the outlet port of the device.

The vanes in each working chamber are adapted to alternately engage their respective vane tracks in fluid relation during predetermined periods of each cycle of the device. That is, when the vane in one working chamber is engaging its respective vane track so as to displace fluid from its inlet passageway to its outlet passageway, the vane in the other working chamber is generally disengaged and thereby permits a free flow of fluid through its associated working chamber. An overlapping in the engagement of the vanes with their respective vane tracks is provided so as to insure a continuous pressurization of the fluid during the entire cycle of the device. Thus, there is no unrestricted fluid communication between the inlet and outlet ports of the device.

A secondary rotor is associated with each of the working chambers and is carried on a common drive shaft having an axis which is parallel to the input shaft of the device and driven thereby. Each of the secondary rotors extends into its respective working chamber such that the outer periphery thereof engages the outer periphery of each of the primary rotors, such as to create a fluid sealing relation to prevent passage of fluid thereby between the inlet and outlet passageways of each of the working chambers. Each of the secondary rotors is provided with one recess which comes into position with respect to the primary rotor at appropriate times to permit the vane carried thereby to pass the secondary rotor without interference. The primary rotors in each working chamber and the vanes carried thereby are moved in timed relationship to one another such that one is displacing fluid while the other is idle with respect to its fluid displacing capacity.

In the preferred embodiment, one sidewall of each working chamber is carried by the input shaft and rotatable therewith and is adapted to be shifted axially inwardly into the working chamber so as to decrease the volume thereof which is availa ble to be displaced by each vane. Means externally operable are adapted to shift the wall member of each working chamber so as to obtain the desired displacement for a particular application.

it is an object of the present invention to provide a variable displacement rotary fluid pump or motor in which the difficulties ofthe prior art in varying the displacement of such devices is reduced or eliminated and to provide an arrangement in which the control of the displacement will tend to be easier and can be more readily effected in a sensitive manner.

It is also an object of this invention to provide such a varia ble displacement fluid pump or motor in which the displacement thereof canbe varied and which does not require a plurality of automatic pressure sensitive valves as required in the aforementioned prior art devices.

DESCRIPTION OF THE DRAWINGS Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the accompanying description of one example of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings wherein like reference numerals refer to like or equivalent parts and in which:

FIG. 1 is a sectional view of a rotary device of the present invention taken on a plane passing through the axis of rotation of the input shaft of the device;

FIG. 2 is a transverse sectional view of the device taken along line 2-2 of FIG. 1;

FIG. 3 is a transverse sectional view along line 3-3 of H6. 1; and

HO. 4 is a transverse sectional view of the device taken along line 4-4 of FIG. 1.

of the device taken DESCRlPTlON OF THE PREFERRED EMBODIMENT T Referring now to FIG. 1, there is shown a fluid pressure energy translating device of the variable displacement type in dicated by the numeral 10, having a housing 12 which consists of a body section l4 sandwiched between end covers 15 and 16. A plurality of bolts indicated by the numeral 18 secure the end covers to the body section 14. The housing 12 is of a generally oval shape having two cylindrical bores extending longitudinally therethrough, the axes of which are parallel and spaced apart from each other and indicated by the numerals, 20, 22, (FIGS. 2 and 3). The device is divided into two pump-- ing sections 24, 26 which are separated from each other by a common partition 28, that is secured to the body section of the housing by means of a plurality of bolts 30 extending through flanges 32, 33 14.

formed at the midsection of the body The pumping sections 24, 26 each define working chambers 34, 36 (FIGS. 2 and 3) respectively, in which there is mounted for rotational movement primary rotors 38, 40. The primary rotors 38, 40 are driven by an input shaft 42 which is provided with a seal 44 and which extends from the housing for connection to a prime mover (not shown). The input shaft 42 is spline connected to the primary rotors 38, 44 respectively at 46, 48 and is rotatably mounted in bearings 50, 52, which are respec tively carried within the end covers l5, l6. O-ring seals 54, 56 prevent leakage at the juncture of the end covers 15, 16 and the body section 14.

Referring to FIGS. 1 and 2 for a description of the pumping section 24, the housing I2 is provided with an inlet supply connection port 58 having an inlet passage 60 leading therefrom and which terminates in the working chamber 34 along the periphery thereof. The periphery of thebore 20 associated with the pumping chamber 34 forms a vane track 62, which is engaged by a vane 64 in a fluid sealing relationship during a predetermined portion of the cycle of the device. The vane 64 is formed integrally with the primary rotor 38. The space formed between the periphery of the bore 20 and the outer periphery of the primary rotor 34 defines the working chamber in which fluid is displaced by the vane 64 during a cycle of the device.

A portion of the innerface of the cover 14 provides a flat surface 68, which abuts the adjacent side face of the primary rotor 38 in a fluid sealing engagement so as to limit the amount of flow between the working chamber 34 and the adjacent faces of the cap 14 and primary rotor 38. The opposite sidewall of the working chamber 34 is provided with a face 69 formed on an axially shiftable cheek plate '70. The face 69 is complementary to the primary rotor 38 and vane 64, such that, the cheek plate 70 is adapted to be shifted into the working chamber 34 between the outer periphery of the primary rotor and the vane track 62. As the cheek plate 70 is shifted axially into the working camber 34, the amount of fluid which can be displaced therein is decreased. The manner in which the cheek plate 70 is axially shifted will be described in greater detail hereinafter.

The cheek plate 70 is comprised of a generally cup-shaped member 71 having a ring section 72 attached to one end thereof by means of bolts 74. The ring section 72 is carried by the shaft 42 at splined portion 76 and is rotatable therewith, thus there is no relative rotational movement between the cheek plate 70 and the primary rotor 38. Axial and radial passageways respectively indicated by the numerals 72, 7S connect the interior of the cup-shaped member 71 with the bore 20 for a purpose to be described hereinafter.

Referring to FIGS. 1 and 3, for a description of the pumping section 26, the primary rotor 40 is encased between the partition member 28 and a second cheek plate 80 within the working chamber 36. The inner surface 82 of the partition member 28 abuts the adjacent side surface of the primary rotor 40 in a fluid sealing engagement so as to prevent leakage of the fluid from the working chamber 36. An outlet passageway 84 (FIG. 2) associated with the pumping section 24 leads directly from the working chamber 34, through the periphery of the bore 20 and into an inlet passageway 86 of the pumping section 26 and to the working chamber 36. A second outlet passageway 88 is located in the pumping section 26 and leads directly from working chamber 36 at a point formed on the periphery of the bore 20 to an outlet port 90 which is adapted to be connected to a fluid user such as a hydraulic motor or the like. The periphery of the bore 20 associated with the pumping chamber 36 forms a vane track 93 which is engaged by a vane formed integrally with the primary rotor 40.

The check plate 80 of the pumping section 26 is identical to the cheek plate 70 and is provided with a face 91 which is complementary to the primary rotor 40 and the vane 95 carried thereby. The check plate 80 is adapted to be shifted axially inwardly into the space 36 formed between the outer periphery of the primary rotor 40 and the vane track 93 formed along the bore surface associated with the space 36, such as to limit the volume therein and thus the amount of fluid which can be displaced by the vane 95.

The check plate 80 is attached to a ring section 92 by means of a plurality of bolts 94 extending therethrough. The bolts 94 are also adapted to carry a driver gear 96 on the opposite side of the ring section for a purpose to be described hereinafter. The ring section 92 and driver gear 96 are splined to the shaft 42 at 97 and are adapted to be driven thereby along with the primary rotor 40, thus there is no relative rotational movement between the cheek plate 80 and the primary rotor 40. Axial and radial passageways respectively indicated by the numerals 89, 99 connect the interior of the cheek plate 80 with the bore 20 and the manner in which the cheek plate 80 is moved axially inward into the working chamber 36 and the purpose of the passageways 89, 99 will be described in greater detail hereinafter.

Each of the pumping sections 24, 26 is provided with a secondary rotor 100, I], respectively, rotatably mounted on a driven shaft I02 which is parallel to and spaced apart from the input shaft 42 and is adapted to be driven thereby by means of the driver gear 96 and a driven gear I04 which meshes therewith and is carried at one end of the driven shaft 102 Suitable bolt means indicated at I08 maintain the driven gear I04 on the driven shaft I02.

The secondary rotors 100, ml are rotatably mounted within the bore 22 and are of such a size that a portion thereof extends downwardly into the bore and into the associated working chambers 34, 36, such that the outer periphery of each of the secondary rotors 100, ml is adapted to engage the outer periphery of the associated primary rotors 38, 40 in a fluid sealing engagement so as to prevent fluid communication between the inlet and outlet passages of the associated chambers for substantial portion of the rotational movement during a cycle of the device. Each of the rotors I00, I0] is provided with longitudinal recesses respectively indicated by the numerals I I0, I12 and are so sized as to permit the vanes 64, 95, respectively, to pass through that portion of the working chambers and the rotors 100, ml without any interference therefrom. During that portion of the cycle wherein the vanes pass through the recesses H0, "2, there is direct fluid communication between the inlet passages and outlet passages of the associated chambers between the outer periphery of the primary rotor and the vane tracks and between the primary rotor and the recess formed in the secondary rotor.

The driven shaft 102 is supported for rotation by means of bearing members 114, I16 respectively associated with the pumping sections 24, 26. The secondary rotors I00, IOI are axially aligned with the bearing members and their adjacent faces abut in a sliding engagement to form a fluid seal to prevent leakage of fluid from the pumping chambers 34, 36, The bearing members I14, 1 I6 are so shaped as to conform to the contour of the inner surface of the housing I2. The upper portion of the bearing members form the bearings in which the driven shaft 102 is rotatably mounted. The lower portion of the bearing members 114, 116 are within the bore 20 and are of a generally cylindrical shape having internal inwardly extending flanges H8, 120, each of which respectively engage the shiftable wall members 70, 80, and are movable therewith. The inwardly extending flanges 118, I20 are securely retained to each of the shiftablc wall members 70, 80 by means of the ring sections 72, 92 and the bolts 74, 94.

It can therefore be seen that the input shaft 42 has a pair of primary rotors 38, 40 rotatably mounted thereon in a pair of working chambers 34, 36 one wall 68, 82 of each working chamber being fixed with respect to the housing, whereas the opposite walls 69, 9] of each chamber is adapted for axial movement relative to the housing and primary rotors, so as to vary the pumping volume of the associated working chamber. Associated with each working chamber is a secondary rotor 100, 101 which is rotatably mounted upon a driven shaft I02 which is parallel to and spaced apart from the input shaft 42 and which is supported by the bearing members 114, 116 which in turn are securely attached to their associated shiftable wall members 70, 80.

It can thus be seen that the driven shaft, the secondary rotors carried thereby, bearing members I14, 116 and the axial shiftable wall members are shiftable as a single unit for controlling the amount of fluid displaced within the working chambers of the pumping sections 24, 26. Thus, as the axially shiftable wall members 70, move into their respective working chambers to decrease the pumping volume therein, the secondary rotors are axially shifted therewith, thus maintaining the fluid sealing relationship between the secondary rotors and their abutting surfaces.

The motor force for shifting the wall members 70, 80 and thus decreasing or increasing the displacement of the pumping chambers 24, 26 as desired, is accomplished by means of a plurality of actuating rod members axially aligned with the input shaft 42 and radially spaced apart therefrom, one of which is illustrated at 122 in FIG. I. The actuating rods I22 are attached to each of the bearing members H4, 116 by any suitable means, such as a threaded bolt or the like, and extends outwardly from the pumping sections 24, 26 through spacer sleeve I24 disposed in the right-hand cover I6 and are attached to externally threaded members I26 by means of bolts I28 threaded to the ends thereof. The spacer sleeve 124 provides proper axial alignment between the pumping sections 24, 26 and the externally threaded members I26. The threaded members 126 are in turn engaged by a control member I30 having a handle extending externally ofthe housing I2. The control member I30 is retained to the cover [6 by means of a cap and screw assembly indicated generally at I32.

It can be seen that by rotating the control member I30 in either a clockwise or counterclockwise direction, the threaded surface I34 thereon will engage the threaded members 126 of the actuating rods I22 and cause the same to be shifted axially inwardly or outwardly into the housing I2, and thus cause the bearing members I14, 116 to be shifted axially back and forth within the housing. As the bearing members "4, I16 are shifted with respect to the housing, the shiftable wall members 70, 80 associated with each working chamber, the driven shaft 102 and the secondary rotors I00, I01 carried thereon are simultaneously shifted, thereby controlling the amount of displacement within each of the working chambers 34, 36. Since the driver and driven gears 96, I04 are carried respectively by the shiftable wall member 80 and driven shaft I02 they too will be axially shifted with respect to the housing when the actuating rods 122 are so shifted. As the shiftable wall members 70, 80 are so shifted inwardly into the space between the rotors 38, 40 and their associated vane track 62, 93, the fluid trapped within the wall members '70, 80 is discharged via the axial and radial passageways 73, 89, 75, 99 into the bore 20 so as to prevent an undue pressure rise within said interiors. Such a pressure rise would inhibit the movement of the wall members 70, 80 and have an adverse effect on the control of the displacement of the device I0. As can be seen in FIG. 1, the axial passageways 73, 89 are continuously in fluid communication with the bore 20 whereas the radial passageways 75, 99 are blocked by the bearing members 114, I16 during a portion of each cycle. The bore 20 may be connected to a reservoir (not shown) or the inlet of the device by means of an external port (not shown).

In operation, fluid enters inlet port 58 and flows into the pressure working chamber 34 by means of the inlet passageway 60. The vane 64 carried by the rotor 38 is rotated through the working chamber and as the same engages the track 62 it carries the fluid within the pumping chamber 34 from the inlet passageway 60 to the outlet passageway 84. Since the vane carried by the primary rotor 40 in the second pumping chamber 26 is diametrically opposed with respect to the first vane, that is it is out of phase therewith, the same will not be engaging its associated vane track 93 while the vane 64 carried by the primary rotor 38 is so engaged except for a light overlapping to insure continuity of pressure. Thus as the first pumping section 24 is displacing fluid there will be an open fluid path between its outlet passageway 84 and the outlet port 90 of the device I0 and fluid will freely flow around the rotor 40. In the same manner, as the vane 64 of the primary rotor 38 within the pumping section 24 is disengaged with the vane track 62 as illustrated in FIG. 2, there is a free flow path around the periphery of the rotor 38 from the inlet passageway 60 to the outlet passage into the pumping section 26. It should be noted that the vanes 64, 95 may engage their respective vane tracks 62, 93 during a substantial portion of each cycle of the device while providing the desired results as hereinbefore mentioned. As can best be seen in FIGS. 2 and 3, the vane 95 carried by the primary rotor 42 is in a fluid sealing engagement with the vane track 93 and the secondary rotor ml is in a fluid sealing engagement with the outer periphery of the primary rotor 40, thus creating a fluid seal between the inlet passageway and the outlet passageway 88 of the pumping section 26. Fluid is thus being pumped from the inlet port 58 of the device via the pumping mechanism 24, through the pumping mechanism 26, out the outlet passage 88, and externally of the pumping device via the outlet port 90, Thus, during every l80 of rotation of the device 10 one vane is pumping fluid while the other is idle with respect to its pumping capability, and during the next I80 of rotation the other vane is pumping fluid while the first vane is idle with respect to its pumping capability.

With a constant input speed to input shaft 42 the amount of fluid displaced by the device 10 will be constant. in order to vary the amount of fluid flow displaced by the device 10, the control member 130 is rotated to shift the actuating rods 122 which is turn shift the bearing members "4, U6 and the shiftable wall members 70, 80 axially into and out of the work ing chambers 34, 36 of each primary rotor 38, 40. When the shiftable wall members 70,80 as viewed in FIG. 1, are shifted to the right of the primary rotors a maximum displacement of the device 10 is obtained and when the shit'table wall members 70, 80 are shifted inwardly, that is, to the left as viewed in FIG. 1, to decrease the amount of volume between the rotors 38, 40 and the vane tracks 62, 93, the displacement of the device 10 is decreased. Thus it can be seen that the fluid output of the device [0 can be varied from zero to full flow or to any point intermediate thereof.

lt should be noted that the sensitivity in the control of the displacement of the device as described hereinbefore may be increased by providing a device having three or more pumping sections in axial alignment. The pumping relationship between the several pumping sections would remain the same, that is, while one pumping section is displacing fluid the remaining pumping sections would be idle with respect to their pumping ca acity. In addition, the angular relationship between the respective inlet and outlet passageways of each pumping section would be varied to accomm date the increase in the number of pumping sections. For example, in a device having four pumping sections each section will displace fluid during percent of a cycle of the device while permitting the free passage of fluid thereby during the remaining 75 percent of the device cycle. The several pumping sections and their associated inlet and outlet passageways are so spaced with respect to one another that each pumping section will alternately displace fluid during 25 percent of the device cycle while the remaining sections are idle. As hereinbefore mentioned, in addition to an overlapping of the engagement of the vanes with their respective vane tracks, so as to insure a constant pressure with the device, the porting passageways may be so designed as to provide for a fluid sealing engagement between the vanes and their associated vane tracks during substantially the entire cycle of the device.

Having thus described the invention, what I claim is as follows;

l. A fluid pressure energy translating device of a variable displacement type comprising:

a housing having a pair of chambers each having lowand high-pressure operating passages, one of which is an inlet passage and the other an outlet passage, one of said chambers having an outlet passage being connected to the inlet passage of the other of said chambers;

a vane track formed in each of said chambers;

a cylindrically shaped primary rotor having a smooth outer periphery and rotatably mounted within each of said vane tracks and defining an annular working space between the periphery of each rotor and its associated vane track;

a radially extending vane carried by each of said primary rotors, one of said vanes engaging in a fluid sealing relationship with the vane track associated with said one chamber for a first predetermined period for displacing fluid from said one chamber inlet passage to said one chamber out let passage, the other of said vanes engaging in a fluid sealing relationship with the vane track associated with said other chamber for a second predetermined period different than said first predetermined period for displacing fluid from said other chamber inlet passage to said other chamber outlet passage;

a cylindrically shaped secondary rotor having a smooth outer periphery and associated with each of said chambers, each of said secondary rotors being mounted for rotational movement therein, one of said secondary rotors having its smooth periphery extending into the annular working space of said one chamber and engaging the smooth periphery of said one chamber primary rotor in a fluid sealing relationship during said first predetermined period and disengaged from said one chamber primary rotor during said second predetermined period, the other of said secondary rotors having its smooth periphery extending into the annular space of said other chamber and engaging the smooth periphery of said other chamber primary rotor in a fluid sealing relationship during said second predetermined period and disengaged from said second chamber primary rotor during said first predetermined period whereby fluid is continuously displaced from said first chamber inlet to said second chamber outlet; and

means selectively movable over said rotor peripheries for decreasing the working space of said chambers and the amount of fluid displaced between said one chamber inlet and said other chamber outlet,

2. The fluid pressure energy translating device as described in claim 1, including a shaft rotatably mounted in said housing; said chambers being axially spaced along said shaft and having said primary rotors carried by said shaft; a second shaft rotatably mounted in said housing being spaced apart and parallel to said first shaft, said secondary rotors being carried by said second shaft and radially spaced from their associated chambers; and, means driving said first and said second shafts in a timed relationship.

3. A fluid pressure energy translating device as described in claim 2, wherein said chambers are ofa cylindrical shape; said primary and secondary rotors being ofa cylindrical shape; said primary rotors having said vanes formed integrally thereon; said secondary rotors having an axial groove formed along a portion of its outer periphery, the rotation of said first and said second rotors being synchronized such that the vane carried by said one chamber primary rotor passes through the recess of the associated secondary rotor during said second predetermined period while the vane carried by said other chamber primary rotor engages its associated vane track; and wherein said other Chamber's vane passes through the recess of said secondary rotor associated with said other chamber during said first predetermined period when said vane carried by said one chamber primary rotor engages said vane track associated with said one chamber.

4. The fluid pressure energy translating device as described in claim 3, wherein said means for decreasing the working space of said chambers comprises:

an axially shiftable wall associated with each of said chambers, said wall being carried by said first shaft and rotatable therewith, said wall having a face complementary to the shape of said first rotor and adapted to be shifted axially inward into said working space to decrease the volume thereof; and means for shifting said wall axially inwardly into said associated working space.

S. A fluid pressure energy translating device of a variable displacement type comprising:

a housing having a pair of cylindrically shaped chambers each having lowand high-pressure operating passages, one of which is an inlet passage and the other an outlet passage, one of said chambers having an outlet passage being connected to the inlet passage of the other of said chambers;

a vane track formed in each ofsaid chambers;

a primary rotor having a cylindrical shape and rotatably mounted within each of said vane tracks and defining an annular working space between the periphery of each rotor and its associated vane track;

a vane integrally formed on each of said primary rotors, one of said vanes engaging in a fluid sealing relationship with the vane track associated with said one chamber for a first predetermined period for displacing fluid from said one chamber inlet passage to said one chamber outlet passage, the other of said vanes engaging in a fluid sealing relationship with the vane track associated with said other chamber for a second predetermined period different than said first predetermined period for displacing fluid from said other chamber inlet passage to said other chamber outlet passage;

a secondary rotor having a cylindrical shape and associated with each of said chambers, each of said secondary rotors being mounted for rotational movement therein, one of said secondary rotors having a portion which extends into the annular working space of said one chamber and engaging the periphery of said one chamber primary rotor in a fluid sealing relationship during said first predetermined period and disengaged from said one chamber primary rotor during said second predetermined period, the other of said secondary rotors having a portion of which extends into the annular space of said other chamber and engaging the periphery of said other chamber primary rotor in a fluid sealing relationship during said second predetermined period and disengaged from said second chamber primary rotor during said first predetermined period whereby fluid is continuously displaced from said first chamber inlet to said second chamber outlet;

a shaft rotatably mounted in said housing, said chambers being axially spaced along said shaft and having said primary rotors carried by said shaft;

a second shaft rotatably mounted in said housing being spaced apart and parallel to said first shaft, said secondary rotors being carried by said second shaft and radially spaced from their associated chambers;

means driving said first and said second shafts in a timed relationship;

each of said secondary rotors having an axial groove formed along a portion of its outer periphery, the rotation of said first and second rotors being synchronized such that the vane carried by said one chamber primary rotor passes through the recess of the associated secondary rotor during said second predetermined period while the vane carried by said other chamber primary rotor engages its associated vane track;

wherein said other chambers vane passes through the recess of said secondary rotor associated with said other chamber during said first predetermined period when said vane carried by said one chamber primary rotor engages said vane track associated with said one chamber; and

means selectively movable over said rotor peripheries for decreasing the working space of said chambers and the amount of fluid displaced between said one chamber inlet and said other chamber outlet, said last mentioned means comprising:

an axially shiftable wall associated with each of said chambers, said wall being carried by said first shaft and rotatable therewith, said wall having a face complementary to the shape of said first rotor and adapted to be shifted axiall inward into said working space to decrease the v0 ume thereof; and means for shifting said wall axially inwardly into said associated working space.

6. The fluid pressure energy translating device as described in claim 5 including bearing means carrying said second shaft, said bearing means being attached to said shiftable wall members and shiftable therewith, wherein axial movement of said bearing members shift said shiftable wall member, said second shaft and second rotors with respect to said associated working spaces.

7. The fluid pressure energy translating device as described in claim 6 wherein said shiftable wall members are carried by said first shaft and rotatable therewith; gearing means carried by said shiftable wall member associated with said other chamber, said gearing means being shiftable therewith and adapted to drive said second shaft in said timed relationship.

8. The fluid pressure energy translating device as described in claim 7 wherein said vane carried by each of said primary rotors is formed integral therewith; and the outer periphery of the chamber wall opposite said shiftable wall members provides a bearing surface on which said secondary rotors are slidably shifted, the outer periphery of said secondary rotors being in a fluid sealing engagement with the outer periphery of said opposite wall.

9. The fluid pressure energy translating device as described in claim 8, including means for shifting said shiftable wall members simultaneously so as to selectively decrease and increase the volume in said working spaces at the same rate, and including second bearing means carried by each of said shiftable wall member, said first mentioned bearing means being carried therein for relative rotational movement therewith, said first, second bearing means being axially shiftable with said shiftable wall members.

10. The fluid pressure energy translating device as described in claim 9, wherein said means for shifting said shiftable wall members comprises a rod attached to said first bearing means and adapted to selectively drive said first bearing means axially relative to said housing, said rod extending externally from said housing; and means for shifting said rod axially. 

1. A fluid pressure energy translating device of a variable displacement type comprising: a housing having a pair of chambers each having low- and highpressure operating passages, one of which is an inlet passage and the other an outlet passage, one of said chambers having an outlet passage being connected to the inlet passage of the other of said chambers; a vane track formed in each of said chambers; a cylindrically shaped primary rotor having a smooth outer periphery and rotatably mounted within each of said vane tracks and defining an annular working space between the periphery of each rotor and its associated vane track; a radially extending vane carried by each of said primary rotors, one of said vanes engaging in a fluid sealing relationship with the vane track Associated with said one chamber for a first predetermined period for displacing fluid from said one chamber inlet passage to said one chamber outlet passage, the other of said vanes engaging in a fluid sealing relationship with the vane track associated with said other chamber for a second predetermined period different than said first predetermined period for displacing fluid from said other chamber inlet passage to said other chamber outlet passage; a cylindrically shaped secondary rotor having a smooth outer periphery and associated with each of said chambers, each of said secondary rotors being mounted for rotational movement therein, one of said secondary rotors having its smooth periphery extending into the annular working space of said one chamber and engaging the smooth periphery of said one chamber primary rotor in a fluid sealing relationship during said first predetermined period and disengaged from said one chamber primary rotor during said second predetermined period, the other of said secondary rotors having its smooth periphery extending into the annular space of said other chamber and engaging the smooth periphery of said other chamber primary rotor in a fluid sealing relationship during said second predetermined period and disengaged from said second chamber primary rotor during said first predetermined period whereby fluid is continuously displaced from said first chamber inlet to said second chamber outlet; and means selectively movable over said rotor peripheries for decreasing the working space of said chambers and the amount of fluid displaced between said one chamber inlet and said other chamber outlet.
 2. The fluid pressure energy translating device as described in claim 1, including a shaft rotatably mounted in said housing; said chambers being axially spaced along said shaft and having said primary rotors carried by said shaft; a second shaft rotatably mounted in said housing being spaced apart and parallel to said first shaft, said secondary rotors being carried by said second shaft and radially spaced from their associated chambers; and, means driving said first and said second shafts in a timed relationship.
 3. A fluid pressure energy translating device as described in claim 2, wherein said chambers are of a cylindrical shape; said primary and secondary rotors being of a cylindrical shape; said primary rotors having said vanes formed integrally thereon; said secondary rotors having an axial groove formed along a portion of its outer periphery, the rotation of said first and said second rotors being synchronized such that the vane carried by said one chamber primary rotor passes through the recess of the associated secondary rotor during said second predetermined period while the vane carried by said other chamber primary rotor engages its associated vane track; and wherein said other chamber''s vane passes through the recess of said secondary rotor associated with said other chamber during said first predetermined period when said vane carried by said one chamber primary rotor engages said vane track associated with said one chamber.
 4. The fluid pressure energy translating device as described in claim 3, wherein said means for decreasing the working space of said chambers comprises: an axially shiftable wall associated with each of said chambers, said wall being carried by said first shaft and rotatable therewith, said wall having a face complementary to the shape of said first rotor and adapted to be shifted axially inward into said working space to decrease the volume thereof; and means for shifting said wall axially inwardly into said associated working space.
 5. A fluid pressure energy translating device of a variable displacement type comprising: a housing having a pair of cylindrically shaped chambers each having low- and high-pressure operating passages, one of which is an inlet passage and the other an outlet passage, one of said chambers having an outlet passage being connected to the inlet passaGe of the other of said chambers; a vane track formed in each of said chambers; a primary rotor having a cylindrical shape and rotatably mounted within each of said vane tracks and defining an annular working space between the periphery of each rotor and its associated vane track; a vane integrally formed on each of said primary rotors, one of said vanes engaging in a fluid sealing relationship with the vane track associated with said one chamber for a first predetermined period for displacing fluid from said one chamber inlet passage to said one chamber outlet passage, the other of said vanes engaging in a fluid sealing relationship with the vane track associated with said other chamber for a second predetermined period different than said first predetermined period for displacing fluid from said other chamber inlet passage to said other chamber outlet passage; a secondary rotor having a cylindrical shape and associated with each of said chambers, each of said secondary rotors being mounted for rotational movement therein, one of said secondary rotors having a portion which extends into the annular working space of said one chamber and engaging the periphery of said one chamber primary rotor in a fluid sealing relationship during said first predetermined period and disengaged from said one chamber primary rotor during said second predetermined period, the other of said secondary rotors having a portion of which extends into the annular space of said other chamber and engaging the periphery of said other chamber primary rotor in a fluid sealing relationship during said second predetermined period and disengaged from said second chamber primary rotor during said first predetermined period whereby fluid is continuously displaced from said first chamber inlet to said second chamber outlet; a shaft rotatably mounted in said housing, said chambers being axially spaced along said shaft and having said primary rotors carried by said shaft; a second shaft rotatably mounted in said housing being spaced apart and parallel to said first shaft, said secondary rotors being carried by said second shaft and radially spaced from their associated chambers; means driving said first and said second shafts in a timed relationship; each of said secondary rotors having an axial groove formed along a portion of its outer periphery, the rotation of said first and second rotors being synchronized such that the vane carried by said one chamber primary rotor passes through the recess of the associated secondary rotor during said second predetermined period while the vane carried by said other chamber primary rotor engages its associated vane track; wherein said other chamber''s vane passes through the recess of said secondary rotor associated with said other chamber during said first predetermined period when said vane carried by said one chamber primary rotor engages said vane track associated with said one chamber; and means selectively movable over said rotor peripheries for decreasing the working space of said chambers and the amount of fluid displaced between said one chamber inlet and said other chamber outlet, said last mentioned means comprising: an axially shiftable wall associated with each of said chambers, said wall being carried by said first shaft and rotatable therewith, said wall having a face complementary to the shape of said first rotor and adapted to be shifted axially inward into said working space to decrease the volume thereof; and means for shifting said wall axially inwardly into said associated working space.
 6. The fluid pressure energy translating device as described in claim 5 including bearing means carrying said second shaft, said bearing means being attached to said shiftable wall members and shiftable therewith, wherein axial movement of said bearing members shift said shiftable wall member, said second shaft and second rotors with respect to said associated working spaces.
 7. The fluid pressure energy transLating device as described in claim 6 wherein said shiftable wall members are carried by said first shaft and rotatable therewith; gearing means carried by said shiftable wall member associated with said other chamber, said gearing means being shiftable therewith and adapted to drive said second shaft in said timed relationship.
 8. The fluid pressure energy translating device as described in claim 7 wherein said vane carried by each of said primary rotors is formed integral therewith; and the outer periphery of the chamber wall opposite said shiftable wall members provides a bearing surface on which said secondary rotors are slidably shifted, the outer periphery of said secondary rotors being in a fluid sealing engagement with the outer periphery of said opposite wall.
 9. The fluid pressure energy translating device as described in claim 8, including means for shifting said shiftable wall members simultaneously so as to selectively decrease and increase the volume in said working spaces at the same rate, and including second bearing means carried by each of said shiftable wall member, said first mentioned bearing means being carried therein for relative rotational movement therewith, said first, second bearing means being axially shiftable with said shiftable wall members.
 10. The fluid pressure energy translating device as described in claim 9, wherein said means for shifting said shiftable wall members comprises a rod attached to said first bearing means and adapted to selectively drive said first bearing means axially relative to said housing, said rod extending externally from said housing; and means for shifting said rod axially. 